The interesting properties of many biological catalysts can be investigated by X-ray diffraction methods. This is due to the fact that it is the three-dimensional arrangement of the various functional groups in the molecule that give the enzyme its very specific properties, and the best method of determining three-dimensional arrangement of atoms in a molecule is by using X-ray as probes. In the present series of investigations, we are studying in detail ribonuclease, an enzyme which has been studied in great detail by various physico chemico and biological methods. Our aim is to establish the relationship between the structure ribonuclease in particular.